Applicant's CH-A-687 368 discloses compression pincers for producing tube joints. Those compression pincers have two compression levers which are adapted to swivel in opposite directions and are provided with a jaw having a mouthlike recess for accommodating the tip of a tube or of a press socket. These compression levers are connected to pincer drive means with which the compression levers can be swivelled for closing the jaws. These and similar compression pincers have been used for a long time for installing water tubing.
In regard to ensure complete sealing of such tube connections, it has been known that such compression pincers experience inevitable wear and that periodic testing is mandatory.
In DE-0-296 02 238 for the wear test there has been proposed a test instrument having a gap-width detector with which the width of the gap between opposite faces of two adjacent compression jaws can be measured. The gap-width detector is configured as an optical sensor with a laser and a receiver of light.
An other test instrument has been known from DE-0-296 04 276. The limit force of the drive means of the tool are checked with this test instrument. This instrument has an electronically controlled linear valve with which the force/path-of-travel characteristic of the drive means is simulated.
The two aforementioned test instruments are comparatively expensive and the test procedure Is laborious. As a rule, these test instruments cannot be used on a building site.